Pot for the manufacture of plate-glass, and the method of making the same.



ished product, p

. by their suitability for oHARLEs H. KERR, or

'IARENTUM, PENN YLVANIA, AssIeNoR' T0 rrr'rsnuacn rLArE GLASS COMPANY, OF PITTSBURGH, PENNSYLVANIA, A CORPORATION OF PENNSYL- vANIA.

' SAME.

POT FOR THIlil MANUFACTURE OF PLATE-GLASS, AND THE METHOD OF MAKING THE Specification of Letters .Patent.

Patented Mar. 6, rear.

\No Drawing. Application filed May 8, 1914, Serial No. 83?,138. Renewed. November 18, 1916. Serial To all whom it may concern:

Be it known that I, CHARLES H. KERR, a citizen of the United States, residing at Tarentum, in the county of Allegheny and State of Pennsylvania, have invented new and useful Improvements in Pots for the Manufacture of 'Plate-Glass, and, the Methods of Making the Same, of which the following is aspecification.

'The invention, relates to the making of the pots employed in the melting of glass batch for the making of plate glass, and has for its primary objects, the production of a pot of maximum durability, and one which will improve the quality of the glass by the elimination of the chief defects causedby the pot, which defects are known in the art as string, stone and Y I. I

Practically all-of the glass pots as now made in this country are produced from clay found in the vicinity of St. Louis, Missouri, such clay being mixed with a relatively small quantity of clay imported from Germany. These clays may differ somewhat, even where produced from the same locality, but are characterized physically the purpose intended, and by the fact that they are low in sand content. Because of their universal use, these clays may be fairly designated as ordinary pot clay, but it. will be understood that where such tended to designate mestic or foreign clays, or mixtures thereof such as are now employed in this country,

term is used it is inor which might be employed. because of their the making of and such relatively other than the pot and it is to be understood that only suchdefects as ordinarily arise from the pot are here referred to. The stone is a piece of foreign and non-transparent material which shows up in the fin that in the melting operation a particl'ajof the clay constitutingthe pot became-{detached from the pot but failed to go into "tity of relatively either the ordinary do- -which have'a high alumina 'jparticles of silica and which is due to thefifact known as string is: similarly caused, the

completesolution in the'glass. The defect I by the pot, is similar to string but of,

much greater size and without clearly de-' fined edges. It has hitherto been impossible toovercome these difiiculties since the material of the pot would not be dissolved uniformly into the glass as the pot washed away and therefore the defects stone, 'string and ream remained.

In overcoming the foregoing difliculties, I have provided a material "or mixture which is less resistant to the washing away into the glass, but which will wash off into the glass in smaller particles and which will become completely dissolved in the glass, so that no trace thereof is left in the shape of stone, string or ream.. I preferably use is composed of the ordinary pot clay mixed with a substantial quanfine grained pure silica sand. This sand is mixed as uniformly as possible throughout the clay, and serves to promote the solution in ticles of clay which wash away 0t. This occurs for distribution of sand clays ticles of clay so that the washing away thereof occurs in relatively small volumes,

from the two reasons, first the through the body of course more readily glass than larger particlesof clay wouldbe.

sand is composed reacts with the glass batch the glass of all par-.

small volumes are of soluble in the mass of The mixture which serves to divide or separate the par- I more readily than do'the particles of clay content, antif7the I vantages .ginsthe addition-of sand; namely l) chang- 7 at the moment of reactien a and solution produce a conditionjoi reac- 1 in. size.

cosity of the glass formed by the solution of the particle of the pot so that it is more easily mixed into the glass, (3) expansion of the send iends to counteract the shrinkage of the cla l have found thetwrhen the send is used in connection with the clay in the proper oroportions substantially all string, stone and ream are eliminated, giving a product of much better. marketable quality. It is true that the send tends to produce What is known as seed in the glass, but such seed, unless present large quantities does not seriously ufiect the value of the 'iroduct, and by maintaining the proper proportion. and of grain of sand. the difi'iculty is largely eliminated. The seed are small gas. bubbles in the glass;

My best results have been secured by the use of from to of send the bulk of which is of a, fineness such that it will pass through a sieve having sixty meshes and be retained by u sieve having a hun drcd. meshes per linear inch (grains about .01 to .005 inch in diameter) such send being round-grained pu'e silica sand with a considerable variation in the size of its mains; However I have found it oossible .g a L to vary the degree of fineness of the sand, l very much and much coarser ."iillld sundthun um specified may be employed. It is also possible to use crushed quartzite rock in place of the send; the grains being very fine if desired, and not necessarily round grains, the onl require ment being that relative line granulated silica of some kind be employed. The limit of come of sand I believe to be up preached ;.n. the grains are aocuhfla? inch As to the rings in the peroentuge of sand which may be employed with beneficial results when compared With the clay Without ilie sand. I re ord 8% as about the lowest a 1 innit. within which the sand coulu be emidoyed with beneficial results, and 30% about the highestpercentage which could he used. the best results bein secured when I 3 e tne amount. or the send HlUIiZIOH lSl-IWGS he- I I tween 3 end r I the total nurture thus p11. .iced. v The quantity of ll1(l.\VlllCll pro rly used also varies with. the

in of. he

fineness oi? send, the finer L send, the .111 r the percentage thereof which may he I? r I Where too much sand is used there m Weaken the point of the iil'lCl become I operation. duced to too results as ,ose

heretofore recited begin to disappear, the string and stone appearing in the glass and the result approaching that secured when the ordinary pot clay is used alone. quantity of sand desirable and its fineness will also vary with the kind of batch employed, with the melting; temperature and with the method of furnace operation.

The use of the sand in the mixture in proper proportion has certain other udvantuges; one of these is that the presenceof the sand tends to decrease the drying shrinkage pf the pot, thus preventing loss.

A further advantage is that send reduces the stickiness of the clay, rendering it of better Working consistency and easier to form into a pot. The pots formed with the proper amount of sand also have a longer average life in the furnace, due to less cracking .lthough they wash away faster at each melt. The invention, While primarily designed and described herein for use With pots for the manufacture of plate glass, is of course of advantage in any container or article which contacts With the molten glass Whether the article be in the form of u pot, or in some other form such for instance as the draw stones employed in the manufacture of Window glass.

l t hut I claim is l. The process of making refractory wells for Contact with molten glass which consists in mixing uniformly through ordinary got clay u quantity of finely divided silica equal. to from 8 to of the total mixture and. forming such mixture into Wz'LllS of the desired configuration.

2. The process of making refractory Walls for contact with molten glass Which consists in mixing uniformly through ordinary pot clay a quantity of finely divided silica equal to from S to 30% of the total mixture and forming such mixture into walls of the desired configuration, thosilica. be ing of such fineness that the major portion of it will consistof'grains less than .05 of an inch in diameter.

The process of i uking receptacles for use in the iminufucture of glass which conin mixing iiini'formly through ordinary pot cluy a. quantity of finely divided silica equal. to from 8 to 30% of Euro, and forming such m'ixtiiire into receptucles.

A The process of making receptacles for use in. theinonu'fncturc oi? glass which con, n mixing un" in *1 through ordinary The tially pure 30 of the total mixture, mixture into pots,

fineness that the .5 will be less than .05 inch silica sand equal to from 8 to and forming such the sand being of such major portion of the grains in diameter.

6. A receptacle for the melting of batch formly therethrough 10 divided silica.

tor the manufacture of adding to ordinary pot clay and mixing un1- formed by adding to ordinary pot clay and mixing unifrom 8 to; 30% of finely 7 A receptacle for the melting trhbatch glass formed by formly therethrough from 8 to 30% of sub- 15 stantially pure silica san d of such fineness subscribing Witnesses.

that the major portion of the grains will be CHARLES H. KERR.

Witnesses:

R. J. Mon'rgoivinnir, M. W. C Z'AD." 

